Claims payment and loss adjustment expenses, maturity refunds and other underwriting expenses, and operating expenses and other general administrative expenses required for insurance underwriting are subtracted from net premiums written and other underwriting profit, and this is then adjusted to reflect other income and expenditure (such as expenses associated with compulsory automobile liability insurance, etc., corresponding to corporate taxes) to calculate underwriting profit (loss).
As for non-life insurance companies, the principal revenue sources are underwriting income and investment income, and underwriting profit indicates the profitability level of underwriting operations.